[gcc r16-3323] libstdc++: Suppress some more additional diagnostics [PR117294]

[Jonathan Wakely]

https://gcc.gnu.org/g:889a1352a2c48320c402aa614c67fe5236ac08ad

commit r16-3323-g889a1352a2c48320c402aa614c67fe5236ac08ad
Author: Jonathan Wakely <jwakely@redhat.com>
Date:   Wed Aug 20 16:50:12 2025 +0100

    libstdc++: Suppress some more additional diagnostics [PR117294]
    
    libstdc++-v3/ChangeLog:
    
            PR c++/117294
            * testsuite/20_util/optional/cons/value_neg.cc: Prune additional
            output for C++20 and later.
            * testsuite/20_util/scoped_allocator/69293_neg.cc: Match
            additional error for C++20 and later.

Diff:
---
 libstdc++-v3/testsuite/20_util/optional/cons/value_neg.cc    | 1 +
 libstdc++-v3/testsuite/20_util/scoped_allocator/69293_neg.cc | 2 ++
 2 files changed, 3 insertions(+)

diff --git a/libstdc++-v3/testsuite/20_util/optional/cons/value_neg.cc b/libstdc++-v3/testsuite/20_util/optional/cons/value_neg.cc
index d3abd03c01af..f6b1886efb99 100644
--- a/libstdc++-v3/testsuite/20_util/optional/cons/value_neg.cc
+++ b/libstdc++-v3/testsuite/20_util/optional/cons/value_neg.cc
@@ -37,3 +37,4 @@ int main()
   }
 }
 // { dg-prune-output "no type .*enable_if" }
+// { dg-prune-output "no matching function for call to 'main..::U::U..'" }
diff --git a/libstdc++-v3/testsuite/20_util/scoped_allocator/69293_neg.cc b/libstdc++-v3/testsuite/20_util/scoped_allocator/69293_neg.cc
index d4be08671f5b..a3fbeba79c8a 100644
--- a/libstdc++-v3/testsuite/20_util/scoped_allocator/69293_neg.cc
+++ b/libstdc++-v3/testsuite/20_util/scoped_allocator/69293_neg.cc
@@ -42,6 +42,8 @@ static_assert(uses_allocator<X, inner_alloc_type>{}, "");
 static_assert(!is_constructible<X, allocator_arg_t, inner_alloc_type>{}, "");
 static_assert(!is_constructible<X, inner_alloc_type>{}, "");
 
+// { dg-error "too many initializers" "" { target c++20 } 0 }
+
 void
 test01()
 {